Spark-pi



ing

*extends the central electrode 13 in JOSEPH ERWINE KUEHNE, F NEWARK, NEWJERSEY.

SPARK-PLUG;

Specification of Letters Patent.

Patented Aug. 26, 1919.

Applicationflled June 20,1918. Serial No. 240,955.

To all whom it may concern Be it known that I, JOSEPH E. KUEHNE, acitizen of the United States, and a resident of Newark, in the county ofEssex and State of New Jersey, have invented a new and ImprovedSpark-Plug, of which the following is a full, clear, and exactdescription.

The object of the invention is to provide a new and improved spark plugarranged to effectively protect the porcelain insulator against injuryliable to be inflictedon accidentally dropping the spark plug ortwistthe same when screwing it up or unscrewing it by the use ofimproper wrenches or other tools. Another object is to prevent rainwater, spray, and other moisture from passing into the spark plug andthereby dis-' posing of one of the causes which induces shortcircuiting. Another object is to permit of readily taking the spark plugapart whenever it is desired to do so, repairing or other, purposes.

\Vith these and other objects in view, the invention consists of certainnovel features of construction as hereinafter shown and described andthen specifically pointed outin the claims.

A practical embodiment of the invention is represented in theaccompanying drawings forming a part of this specification, in whichsimilar characters of reference indicate corresponding parts in bothviews.

Figure 1 is a sectional side elevation of the spark plug with theporcelain insulator and the electrode shown in section; an

Fig. 2 is a sectional side elevation of the head or cap of the plug.

The shell of the spark plug is provided with the usual threaded end 11screwing into the tap opening of the cylinder on which the spark plug isused. The spark plug is provided with the usual electrodes 12 and 13, ofwhich the electrode 12 attached to the end 11 of the shell 10. Theelectrode 13 is the central electrode and is in the form of a rod.

Into the shell 15 of-a conical plug polygonal base 17 for theapplication of a wrench or other tool to screw the plug 16 into theshell'10 or out of the same. The plug 16 is provided at its lower andupper ends with interior seats 18, 19, of which the d by the enlargement20 of seat 18 is engage I the porcelain insulator 21 through which theusual 16 provided with a for cleaning,

10 screws the threaded end manner, The lower portion of the porcelaininsulator 21 extends within the shell 10 and the portion directly abovethe enlargement 20 extends through the plug 16 and its upper end extendsinto a large bore of a head or-cap 26 made of bakelite, hard rubber,fiberor other suitable insulating material. The header cap 26 isprovided with a reduced portion 27 fitting into the seat 19 of the plug16, and the exterior surface of the head or cap is made conical andforms a continuation of the exterior surface of the pl11g16. The upperend of the head or cap 26 is provided with a central small bore 28through which extends the upper threaded end of the central electrode13. A lock nut 30 screws on the upper threaded end 29 of the centralelectrode 13 against a spring washer 31 held on the top of the head orcap 26. and a binding nut 32 screws on the threaded end 29 for clampinga condpcting wire in position on the end 29 of the central electrode 13and against the lock nut 30. A collar is arranged on the centralelectrode 13 and is seated on a shoulder 36 formed in the porcelaininsulator 21 'to draw the enlarged portion '20 in firm contact with apacking 40 held on the bottom of the seat 18 on screwing up the lock nut30 on the threaded end 29 of the central electrode 13.

From the foregoing it will be seen that by the arrangement described,the porcelain insulator 21 is wholly contained within the shell 10,- theplug 16 and its head or cap 26, and consequently the said porcelaininsulator is not liable to be injured on dropping the spark plug or ontwisting the same when screwing up or unscrewing it from the cylinder.It will also be noticed that the several )arts forming the spark plugcan be readi y taken apart for, cleaning, repairing or other purposes,it being understood that it is only necessary for the operator tounscrew the plug 16 from the shell 10 and to unscrew the nuts 32 and 30from the threaded end 29 of the central electrode 13 to allow' trode 13through the porcelain insulator 21 and the said head or cap 26 thecentral electrode is held out of contact with the metallic parts of thespark plug and short circuiting is prevented. It will also be noticedthat the head or cap 26 forms a continuation of the plug 10 andeffectively prevents Water or moisture from passing into the spark plugthus disposing of another cause for short circuiting. It is understoodthat any water which may drop onto the plug 16 and its cap 26 is readilyshed owing to the conical shape given to the said parts. By giving theplug 10 and its head or cap 26 a conical shape no undesirableprojections are formed. \Vhen the internal combustion engine on which.the spark plug is used is stopped the porcelain insulator :21 is usuallyin a hot state, but as it is protected against cool breezes, water orthe like, it is not liable to crack or break by extraneous influences ofa lower temperature and the insulator can cool off gradually.

aving thus described my invention, I claim as new and desire to secureby Letters Patent:

1. A spark plug, comprising a shell provided with an electrode, aconical plug screwing into the shell and having at its lower end a seat,a conical removable head of insulating material mounted on the upper endof the plug so that its exterior surface is flush with the exteriorsurface of the plug, an insulator, the insulator being wholly within theshell, plug and head, and a central electrode extending through theinsulator and the insulating head of the plug and binding means carriedby the central electrode to hold the plug, insulated head, and insulatorin juxtaposition provided with a binding nut.

A spark plug, comprising a shell provided with an electrode, a conicalplug screwing into the shell and having internal seats at its upper andlower ends, a conical removable head having a reduced lower end fittingin the seat at the upper end of the plug, an insulator having aninternal shoulder and an enlargement seated on the lower seat of theplug, the insulator being wholly within the shell, plug and head, acentral electrode extending through the insulator and insulating headand having gaging the shoulder of the insulator, and binding and lockingnuts on the threaded end of the electrode.

JOSEPH ERlVINE KUEHNE.

a collar en- 5(

